Pension and Other Postretirement Benefits (Schedule of Components of Periodic Benefit Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2019
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 38	$ 35
Interest cost	30	39
Total periodic benefit costs	64	48	$ 51
Pension Benefits | Direct Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	38	35	19
Interest cost	30	39	30
Expected return on plan assets	(50)	(55)	(30)
Amortization of deferred losses	44	28	11
Other	2	1	7
Net periodic benefit costs	64	48	37
Pension Benefits | Shared Plans
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit costs- Shared Plans	0	0	14
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	2
Interest cost	2	3
Total periodic benefit costs	5	6	7
Postretirement Benefits | Direct Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	2	1
Interest cost	2	3	2
Expected return on plan assets	0	0	0
Amortization of deferred losses	1	1	1
Other	0	0	(1)
Net periodic benefit costs	5	6	3
Postretirement Benefits | Shared Plans
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit costs- Shared Plans	$ 0	$ 0	$ 4